In Applicant's prior U.S. Pat. No. 4,021,283 dated May 3, 1977, a system is disclosed for aspetic packaging. This system includes a web of bags which can be manufactured with sterile interiors and subsequently filled and sealed without exposure of the sterile bag interiors to contaminating organisms.
The web of bags is formed as a system of interconnected bags which communicate with a common, continuous passage extending across the mouths of the bags and through which the filling process is performed. The filling pipe for the system is inserted in this passage to fill the bags without exposing their interiors to ambient. The mouths of the bags are then sealed while the pipe is still positioned in the passage, the web of bags severed beneath the pipe and the resulting offal reclaimed for reprocessing.
In some environments and particularly when packaging certain types of food stuffs, it is desirable to provide a high degree of gas and light imperviousness. While the thermoplastic materials which may be advantageously used in the system disclosed in Applicant's above noted prior patent provide excellent moisture vapor and bacteria barrier properties, generally such materials do not provide a high degree of gas and light imperviousness.
To overcome this deficiency it has been proposed that material having these properties be laminated to a sterile tube of thermoplastic material. One type of material which provides the degree of gas and light impermeability desired is metal foil.
In prior applications metal foil has been applied to preformed sheets or other stock forms of thermoplastic material. Generally this is accomplished by first bonding to the foil a material which then serves to adhere the foil to the thermoplastic material.
In U.S. Pat. No. 2,962,843, dated Dec. 6, 1960, a process is disclosed for shaping about an extruded tube of film a concentric tube of paper or other material which extends completely about the extruded tube and is provided with a lap or other type seam. In the composite tube formed in accordance with the process disclosed in U.S. Pat. No. 2,962,843 the outer layer of paper or other material is completely co-extensive with the inner film layer throughout the entire circumference of the tube.
Thus, if a tube of this type were somehow adapted to a system of the type disclosed in Applicant's above noted prior patent, the filling operation would not be visible, a portion of the outer layer of material would be wasted in the subsequent severing operation following filling and sealing, and the inner layer of thermoplastic material would not be readily reclaimable, of which the latter two are important economic considerations.